[PHP / Imageresize]-Problem mit den Thumbnails

function resizepic($imgfile,$file_size=0) {
	$query=mysql_query("SELECT * FROM `config`");
	$config=mysql_fetch_array($query);
	$thfile="tn_".$imgfile;
	$max_width=$config['thumbbreite'];
  	$max_height=$config['thumbhoehe'];


  	list($org_width, $org_height, $orgtype) = getimagesize($imgfile);


  	$faktor = $org_width/$org_height;
  	$new_width = $max_width;
  	$new_height = $new_width / $faktor;


  	if ($org_width <= $max_width){
  		$new_width = $org_width;
         	$new_height = $org_height+16;
  	}
  	if ($new_height > $max_height) {
    		$faktor2 = $max_height / $new_height;
    		$new_height = $max_height;
    		$schnipp_height = $org_height * $faktor2;
  	} else {
         	$schnipp_height = $org_height;
         }


	switch ($orgtype) {
	    case 1 :
	      $im = imagecreatefromgif($imgfile);
	      break;
	    case 2 :
	      $im = imagecreatefromjpeg($imgfile);
	      break;
	    case 3 :
	      $im = imagecreatefrompng($imgfile);
	      break;
	}


  	if ($im) {
    		$tn = imagecreatetruecolor($new_width,$new_height);
    		if ($tn) {
      			// Alternativ-Funktion: Bild wird verkleinert!
	      		imagecopyresized($tn,$im,0,0,0,0,$new_width,$new_height,$org_width,$schnipp_height);
	      		$PA_x=0;
	      		$PA_y=0;
	      		imagecopymerge($tn,$im, 0, 0, $PA_x, $PA_y, $new_width, $new_height, 100);
	      		$schwarz = ImageColorAllocate ($tn, 0, 0, 0);
	      		$weiss = ImageColorAllocate ($tn, 255, 255, 255);
	      		imagefilledrectangle ($tn, 0, $new_height-16, $new_width, $new_height, $schwarz );
	      		$tntext = $org_height."x".$org_width;
      				if ($file_size != 0) $tntext .= " - ".number_format(($file_size/1024),2,",",".")." kb";
      				ImageString ($tn, 2, 10, $new_height-15, $tntext, $weiss);
      				switch ($orgtype) {
	                          case 1 :
	                            imagegif($tn,$thfile);
	                            return 1;
	                            break;
	                          case 2 :
	                            imagejpeg($tn,$thfile,90);
	                            return 2;
	                            break;
	                          case 3 :
	                            imagepng($tn,$thfile);
	                            return 3;
	                            break;
	                	}
      			imagedestroy($tn);
      			imagedestroy($im);
    		}
  	}
  	return false;
}